In recent years, flash memory has become the most common form of non-volatile memory, mostly because it permits high density of memory cells, maintains low manufacturing cost and is generally reliable as a form of secondary storage. Conventional flash memory, however, suffers from a defect in that it degrades the more often it is reprogrammed, a disadvantage that grows more prominent as memory density continues to increase. Additionally, conventional flash memory operates too slowly to be used as a general substitute for random access memory (RAM).
Industry has therefore searched for other non-volatile alternatives to flash memory; some proposed devices are based on memory cells that are controlled to change their effective resistance, and thereby store information. These devices generally have not yet been widely commercialized owing to silicon processing variations (a) that cause some cells to fail, such that they cannot be properly set or reset and (b) that, for those cells which do not fail, create unacceptable variation in the stimuli needed to form (i.e., condition), set and reset those cells.
What is needed are non-volatile devices and structures that exhibit greater consistency in terms of their characteristics, as well as methods for making these devices. The present invention addresses these needs and provides further, related advantages.